Rotor for line-start reluctance motor

ABSTRACT

The present invention discloses a rotor for a line-start reluctance motor which improves core area efficiency to make flux flow in one direction. The rotor for the line-start reluctance motor includes a core having an axis coupling hole in a coupling direction of a shaft, a plurality of bars formed in the periphery of the core, and a plurality of flux barriers, one and the other ends of the flux barriers approaching the bars formed in first and second areas facing each other at a predetermined angle on a central line of a first axis on a core plane vertical to the coupling direction, at least parts of the centers of the flux barriers passing through a third or fourth area between the first and second areas, surrounding the axis coupling hole at predetermined intervals.

TECHNICAL FIELD

The present invention relates to a rotor for a line-start reluctancemotor, and more particularly to, a rotor for a line-start reluctancemotor which improves core area efficiency to make flux flow in onedirection.

BACKGROUND ART

A line-start reluctance motor is a single phase power alternating motorfor performing constant speed motion. It is a combination type of aninduction motor and a reluctance motor. The line-start reluctance motorincludes a stator for forming a rotating magnetic field by alternatingcurrent applied to windings, and a rotor positioned in the stator androtated by the rotating magnetic field formed by the stator. Theline-start reluctance motor uses a rotary force generated when flux ofthe stator passes through the rotor and the rotor moves in a directionof decreasing reluctance (magnetic resistance). That is, in the startoperation, the line-start reluctance motor starts to be rotated by usingstart torque generated by mutual operations of variations of the flux ofthe stator and current deserted in bars as in an induction motor, andafter the start operation, the line-start reluctance motor is rotated ina constant speed by using reluctance torque making the flux of thestator flow through a core portion of the rotor.

As disclosed in U.S. Laid-Open Patent Application 3,862,446, a rotor fora two pole synchronous reluctance motor includes a core having a pair ofeffective oppositely disposed salient poles for improving initial startproperties of the reluctance motor, a plurality of circumferentiallyspaced interconnected conductors in each salient pole portion adjacentto the periphery thereof forming main pole windings, the main conductorsof each pole encompassing 90 mechanical degrees of the rotor core, fluxbarriers formed in and extending across the core between the main polewindings with the ends thereof circumferentially spaced from the mainpole winding, and at least one additional secondary conductor located inthe space between the ends of each main pole winding and each end of theflux barrier adjacent to the periphery of the core, the space betweenthe ends of the main pole windings and the circumferentially nearestsecondary conductor being greater than the space between any twoadjacent main conductors, the conductors being connected together toform a squirrel.

According to U.S. Laid-Open Patent Application 6,604,134, a rotorassembly for a synchronous reluctance motor includes a shaft, a corehaving a plurality of shaped supports, the supports being configured,dimensioned and positioned to define a plurality of channels, the corebeing mounted on the shaft, a plurality of generally arcuate rotorsections, each of the rotor sections secured within a respective channelof the core, and a plurality of bands disposed circumferentially aboutthe rotor sections for securing the rotor sections to the core.

In addition, as suggested in U.S. Laid-Open Patent Application6,066,904, a mechanical device selected from a synchronous reluctancemachine and a switched reluctance machine includes a rotor having acentral axis, the rotor formed by a plurality of radial laminations, thelaminations being stacked axially and being made of grain-orientedmagnetic material having a direction of highest magnetic permeability,the direction of highest magnetic permeability of the magnetic materialbeing parallel to a plane that bisects each of the laminations, each ofthe laminations having at least one pair of internal slots, at least onepair of internal slots being aligned in a direction at least generallyparallel to the plane, and at least one pair of internal slots beingsymmetric about the plane.

As described above, the conventional rotors have a number of complicatedelements, which consumes a lot of time and expenses during theproduction.

In addition, the conventional rotors require special elements (forexample, conductors made of magnetic material).

The conventional arts do not provide maximum outputs and efficiency ofthe rotor based on a difference between flux density in a high permeabledirection (for example, d axis) and flux density in a low permeabledirection (for example, q axis).

Furthermore, the conventional arts do not provide shapes and alignmentsof bars for giving efficient output properties to the rotor bypreventing magnetic saturation in the core.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a rotor for aline-start reluctance motor which reduces time and expenses inproduction by using simple elements.

Another object of the present invention is to provide a rotor for aline-start reluctance motor which uses general stacked cores.

Yet another object of the present invention is to provide a rotor for aline-start reluctance motor which has high outputs and efficiency, bymaximizing a difference between flux density in a high permeabledirection and flux density in a low permeable direction.

Yet another object of the present invention is to provide a rotor for aline-start reluctance motor which has efficient start properties bychanging shapes and alignments of bars.

In order to achieve the above-described objects of the invention, thereis provided a rotor for a line-start reluctance motor including: a corehaving an axis coupling hole in a coupling direction of a shaft; aplurality of bars formed in the periphery of the core; and a pluralityof flux barriers, one and the other ends of the flux barriersapproaching the bars formed in first and second areas facing each otherat a predetermined angle on a central line of a first axis on a coreplane vertical to the coupling direction, at least parts of the centersof the flux barriers passing through a third or fourth area between thefirst and second areas, surrounding the axis coupling hole atpredetermined intervals.

Preferably, the flux barriers surround the axis coupling hole in acircular arc shape.

Preferably, the flux barriers are continuous.

Preferably, the flux barriers are symmetric on a second axis vertical tothe first axis on the core plane.

A rate of an area of the flux barriers to a whole area of the core planeis preferably 0.35 to 0.45, more preferably, 0.39.

A rate of a whole width of the flux barriers to a width between the axiscoupling hole and the outer circumference of the core is preferably 0.35to 0.45, more preferably 0.405.

Central lines of one and the other ends of the flux barriers and centrallines of the bars which the flux barriers approach are preferablydisposed in the same directions, the central lines of the bars facingthe center of the core. More preferably, the central lines of the barsand the central lines of the flux barriers are disposed on the samelines.

Preferably, a width of the flux barriers is equal to or smaller thanthat of the bars which the flux barriers approach.

Intervals between the flux barriers and the bars which the flux barriersapproach are preferably constant, more preferably less than 0.35 mm.

Preferably, a width of the outer circumferences of the bars adjacent tothe outer circumference of the core is larger than that of the innercircumferences of the bars adjacent to the flux barriers.

Preferably, some of the bars in the first and second areas are notadjacent to the flux barriers.

Preferably, intervals between the bars and the outer circumference ofthe core are all the same.

Preferably, the flux barriers are formed between the bars in the thirdand fourth areas.

Preferably, an area of the bars in the third and fourth areas is smallerthan that of the bars in the first and second areas.

Preferably, intervals between the bars in the third and fourth areas aresmaller than those between the bars in the first and second areas.

Preferably, a width of the outer circumferences of the bars in the thirdand fourth areas is larger than that of the outer circumferences of thebars in the first and second areas.

An angle of the first and second areas is preferably 100 to 110°, morepreferably, 104°.

Preferably, a length of the bars in the first and second areas is largerthan that of the bars in the third and fourth areas.

Preferably, at least one flux barrier is formed between a common tangentline of the inner circumferences of the bars in the first and secondareas and a common tangent line of the inner circumferences of the barsin the third and fourth areas.

According to one aspect of the invention, a rotor for a line-startreluctance motor includes: a core having an axis coupling hole in acoupling direction of a shaft; a plurality of bars formed in theperiphery of the core; and a plurality of flux barriers having theirboth ends aligned in one direction to approach the bars, respectively,central lines of the bars facing the center of the core and centrallines of both ends of the flux barriers being formed in the samedirections.

According to another aspect of the invention, a rotor for a line-startreluctance motor includes: a core having an axis coupling hole in acoupling direction of a shaft; a plurality of bars formed in theperiphery of the core; and a plurality of flux barriers having theirboth ends aligned in one direction to approach the bars, respectively, awidth of the flux barriers being equal to or smaller than that of thebars which both ends of the flux barriers approach.

According to yet another aspect of the invention, a rotor for aline-start reluctance motor includes: a core having an axis couplinghole in a coupling direction of a shaft; a plurality of bars formed inthe periphery of the core; and a plurality of flux barriers aligned inone direction, a length of the bars disposed in an alignment directionof the flux barriers being larger than that of the bars disposed in avertical direction to the alignment direction of the flux barriers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a plane view illustrating a rotor for a line-start reluctancemotor in accordance with a first embodiment of the present invention;

FIG. 1B is a plane view illustrating the area-divided rotor of FIG. 1A;

FIGS. 1C and 1D are partial plane views of FIG. 1A;

FIG. 1E is a partial enlarged view of FIG. 1A;

FIGS. 2A and 2B are plane views illustrating a rotor for a line-startreluctance motor in accordance with a second embodiment of the presentinvention;

FIG. 2C is a partial plane view of FIG. 2A;

FIG. 3 is a plane view illustrating a rotor for a line-start reluctancemotor in accordance with a third embodiment of the present invention;

FIG. 4 is a plane view illustrating a rotor for a line-start reluctancemotor in accordance with a fourth embodiment of the present invention;

FIG. 5 is a plane view illustrating a rotor for a line-start reluctancemotor in accordance with a fifth embodiment of the present invention;and

FIG. 6 is a plane view illustrating a rotor for a line-start reluctancemotor in accordance with a sixth embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

FIGS. 1A and 1B are plane views illustrating a rotor for a line-startreluctance motor in accordance with a first embodiment of the presentinvention.

Referring to FIG. 1A, a rotor 10 includes a core 11 having an axiscoupling hole 12 formed in a coupling direction of a shaft (not shown).The core 11 includes a plurality of bar insertion holes 13 in itsperiphery, and a plurality of bars 14 are inserted into the barinsertion holes 13. In addition, the core 11 has a plurality of fluxbarriers 15 extending toward a first axis vertical to the couplingdirection of the shaft (hereinafter, referred to as ‘couplingdirection’), and being symmetric to each other on a second axis verticalto the first axis. Parts of the core 11 between the plurality of fluxbarriers 15 which flux flows through are flux paths 16.

In detail, the rotor 10 is comprised of a plurality of stacked coreplanes, and the core 11 does not require special magnetic materials.

The bars 14 are inserted into the bar insertion holes 13 of the core 11,and extend toward the same positions of the stacked core planes.Generally, the bars 14 include aluminum elements.

The flux barriers 15 are formed by removing parts of the core 11 andfilling them with air. The flux barriers 15 have their one and the otherends aligned and extended in the first axis direction, and have at leastparts of their centers extended to surround the axis coupling hole 12 atpredetermined intervals, to easily pass the flux in the first axisdirection and minimize passing density of the flux in the second axisdirection. That is, the flux barriers 15 generate the maximum fluxdensity in the first axis direction and the minimum flux density in thesecond axis direction vertical to the first axis direction, therebyremarkably improving a start force of the rotor 10.

In addition, the flux barriers 15 are disposed to surround the axiscoupling hole 12 in a circular arc shape, and thus improve a rotaryforce and start performance of the rotor 10, without interrupting flowof the flux from a stator (not shown).

In the related arts, the flux barrier is formed in an intermittent shapehaving a bridge in its center. Accordingly, magnetic saturation isgenerated in the bridge portion, to interrupt flow of the flux. In orderto prevent the magnetic saturation, the core 11 includes the continuousflux barriers 15. Such continuous flux barriers 15 prevent the magneticsaturation, facilitate flow of the flux, and thus improve startperformance of the rotor 10. Moreover, the continuous flux barriers 15reduce time and expenses during the production of the rotor 10.

If the flux barriers 15 occupy a large area of the core 11 of the rotor10, an area of the core 11 which the flux flows through in the firstaxis direction decreases, to cause the magnetic saturation in the core11. It is thus necessary to control a rate of the area of the magneticbarriers 15 to the area of the core 11 (or area of the flux paths 16). Awidth of the flux barriers 15 is also an important factor forfacilitating flow of the flux. That is, when the width of the fluxbarriers 15 is excessively large, a width of the core 11 which the fluxflows through decreases, and when the width of the flux barriers 15 isexcessively small, it is difficult to maximize a difference between fluxdensity in the first axis direction and flux density in the second axisdirection. As a result, it is necessary to control a rate of a wholewidth of the flux barriers 15 to a width between the axis coupling hole12 and the outer circumference of the core 11.

Some 14 a of the bars 14 can be formed not to be adjacent to the fluxbarriers 15 in consideration of the area of the flux barriers 15, and toform the flux barriers 15 symmetric to each other in the first axisdirection.

As illustrated in FIG. 1B, the rotor 10 can be divided into first andsecond areas facing each other at a predetermined angle on a centralline of the first axis on the plane of the core 11 vertical to thecoupling direction, and also be divided into third and fourth areasbetween the first and second areas. Here, d axis used as the first axisin FIG. 1A indicates a high permeable direction of the flux, and q axisused as the second axis in FIG. 1A indicates a low permeable directionof the flux.

In detail, the bars 14 in the first and second areas are adjacent to oneand the other ends of the flux barriers 15, so that the flux (indicatedby bold solid lines) can easily flow between the bars 14 and through theflux paths 16 extended therefrom. Accordingly, the first axis, namely daxis becomes the high permeable direction axis of the flux. The centersof the flux barriers 15 pass through the third or fourth area,surrounding the axis coupling hole 12 at predetermined intervals. Theflux does not flow between the bars 14 in the third and fourth areas,and thus the second axis, namely q axis becomes the low permeabledirection axis of the flux.

FIG. 1C is a partial plane view of FIG. 1A. As shown in FIG. 1C, inorder to increase a difference between flux density in the first axis (daxis) direction and flux density in the second axis (q axis) direction,in the rotor 10, intervals (c) between the bars 14 in the second axisdirection (namely, third and fourth areas) are smaller than intervals(a) and (b) between the bars 14 in the first axis direction (namely,first and second areas). Thus, the magnetic saturation is generated inthe intervals (c), thereby minimizing flow of the flux from the statorto the core 11 in the second axis direction. That is, the second axisdirection bars 14 serve as barriers.

FIG. 1D is a partial plane view of FIG. 1A. As depicted in FIG. 1D, oneand the other ends of the flux barriers 15 approach the bars 14 and/orbar insertion holes 13 symmetric on the second axis. Intervals (d)between the flux barriers 15 and the bars 14 and/or bar insertion holes13 are constant. Thus, generation of the saturation of the flux flowingin the first axis direction is minimized in the intervals (d), andintensity of the rotor 10 is maintained. Accordingly, one and the otherends of the flux barriers 15 are formed according to shapes of the innercircumferences of the bar insertion holes 13 and/or bars 14 (moreexactly, surfaces adjacent to one and the other ends of the fluxbarriers 15). Here, the intervals (d) are preferably less than 0.35 mm.

In addition, the bar insertion holes 13 and/or bars 14 are formed toequalize intervals (e) between the bars 14 and the outer circumferenceof the core 11.

FIG. 1E is a partial enlarged view of FIG. 1A. As illustrated in FIG.1E, a central line I of one and/or the other end of the flux barrier 15and a central line II of the bar 14 which the flux barrier 15 approaches(line equally dividing the area of the bar 14 and facing the axiscoupling hole 12 (or center of the core 11)) are disposed on the sameline. Such an alignment prevents the flux flowing from the stator to thecore 11 from colliding against the flux barriers 15, and makes the fluxeasily flow through the core 11 and/or flux paths 16.

Still referring to FIG. 1E, a width (f) of the flux barrier 15 is equalto or smaller than a width (g) of the bar 14 which the flux barrier 15approaches. Such a width difference prevents both ends of the fluxbarriers 15 from interrupting flow of the flux from the stator, andmakes the flux easily flow through the core 11 and/or flux paths 16.

FIGS. 2A and 2B are plane views illustrating a rotor for a line-startreluctance motor in accordance with a second embodiment of the presentinvention. The rotor 20 of FIG. 2A has the aforementioned properties ofthe rotor 10 of FIG. 1A, and also has additional properties describedbelow.

As shown in FIG. 2A, flux enters the rotor 20 in the d axis directionand flows through flux paths 26, but rarely flows in the q axisdirection. The detailed explanation of the rotor 20 will later beexplained with reference to FIG. 2B.

Still referring to FIG. 2A, as identical to the rotor 10 of FIG. 1A, therotor 20 is divided into first and second areas facing each other at apredetermined angle α on a central line of d axis on a core planevertical to a coupling direction, and also be divided into third andfourth areas between the first and second areas. In consideration of astart force of the rotor 20, the angle α is preferably 100 to 110°, morepreferably, 104 .

The rotor 20 is provided with additional properties in bars 24 and fluxbarriers 25 in the third and fourth areas.

In detail, an area of the bars 24 in the third and fourth areas is equalto or smaller than that of the bars 24 in the first and second areas.That is, the bars 24 having the reduced area in the third and fourthareas perform the same function as the flux barriers 25. However,intervals between the outer circumferences of the bars 24 and the outercircumference of a core 21 in the third and fourth areas are identicalto intervals between the outer circumferences of the bars 24 and theouter circumference of the core 21 in the first and second areas. Theother characteristics are described below.

As depicted in FIG. 2B, a width (h) of the outer circumferences of thebars 24 in the first and second areas is equal to or smaller than awidth (i) of the outer circumferences of the bars 24 in the third andfourth areas. Accordingly, the flux easily flows around the bars 24 inthe first and second areas, and less flows around the bars 24 in thethird and fourth areas. As a result, the bars 24 in the third and fourthareas perform the same function as the flux barriers 25.

As explained in FIG. 1A, the properties in the area and width of thebars 24 in the third and fourth areas are operated simultaneously orseparately with the properties in the intervals of the bars 24 in thethird and fourth areas, so that the bars 24 in the third and fourthareas can perform the same function as the flux barriers 25, therebyremarkably increasing a difference between flux density on d axis andflux density on q axis.

In the direction of an axis coupling hole 22, a length (j) of the bars24 in the first and second areas is larger than a length (k) of the bars24 in the third and fourth areas. Such a length difference influencesthe properties in the area and width of the bars 24 and minimizes thewhole area of the bars 24 in the third and fourth areas, therebyimproving efficiency of the core area. In addition, at least one fluxbarrier 25 a can be formed between a common tangent line III of theinner circumferences of the bars 24 in the first and second areas and acommon tangent line IV of the inner circumferences of the bars 24 in thethird and fourth areas. As the bars 24 in the third and fourth areasperform the same function as the flux barriers 25, the flux barrier 25 aremarkably increases the difference between flux density on d axis andflux density on q axis.

As described above, when the flux barriers 25 and 25 a occupy a largearea of the core 21 of the rotor 20, an area of the core 21 and/or fluxpaths 26 which the flux flows through in the d axis direction decreases,to generate magnetic saturation in the core 21. It is thus necessary tocontrol a rate of the area of the flux barriers 25 and 25 a to the areaof the core 21. In the rotor 20 of the invention, a rate of a whole areaof the flux barriers 25 and 25 a to a whole area of the core plane ispreferably 0.35 to 0.45, more preferably, 0.39.

FIG. 2C is a partial plane view of FIG. 2A. In addition to the rate ofthe area, a width of the flux barriers is an important factor forfacilitating flow of the flux. That is, when the width of the fluxbarriers 25 and 25 a is excessively large, the width of the core 21which the flux flows through decreases, and when the width of the fluxbarriers 25 and 25 a is excessively small, it is difficult to maximizethe difference between flux density in the d axis direction and fluxdensity in the q axis direction. Preferably, a rate of a whole width(L1) of the flux barriers 25 and 25 a (L1=La+Lb+Lc; total widths of theflux barriers 25 and 25 a formed in the width L) to a width (L) betweenthe axis coupling hole 22 and the outer circumference of the core 21 is0.35 to 0.45, more preferably 0.405.

FIG. 3 is a plane view illustrating a rotor for a line-start reluctancemotor in accordance with a third embodiment of the present invention.The rotor 30 of FIG. 3 has the whole properties of the rotor 10 of FIG.1A and some properties of the rotor 20 of FIG. 2 (for example, exceptthe flux barrier 25 a), and also has additional properties.

In detail, in a core 31 of the rotor 30, bars 34 in third and fourthareas are installed in flux barriers 35 a. That is, the flux barriers 35a are formed between the bars 34 in the third and fourth areas. Fluxentering between the bars 34 do not flow into the core 31 due to theflux barriers 35 a. Therefore, a difference between flux density on daxis and flux density on q axis considerably increases.

FIG. 4 is a plane view illustrating a rotor for a line-start reluctancemotor in accordance with a fourth embodiment of the present invention.The rotor 40 of FIG. 4 has the whole properties of the rotor 10 of FIG.1A and the whole properties of the rotor 20 of FIG. 2A, and also hasadditional properties.

In detail, a width (m) of the outer circumferences of bars 44 adjacentto the outer circumference of a core 41 is equal to or larger than awidth (n) of the inner circumferences of the bars 44 adjacent to fluxbarriers 45. Especially, such a structure is formed in the bars 44 infirst and second areas, and makes flux entering the core 41 obtainsufficient intervals between the bars 44. It prevents magneticsaturation, and facilitates flow of the flux entering the core 41. Asthe width (n) of the inner circumferences of the bars 44 decreases, anarea of gaps 47 between the bars 44 and the flux barriers 45 relativelydecreases. Accordingly, the magnetic saturation is prevented between thegaps 47.

FIG. 5 is a plane view illustrating a rotor for a line-start reluctancemotor in accordance with a fifth embodiment of the present invention.The rotor 50 of FIG. 5 has the whole properties of the rotor 10 of FIG.1A, the whole properties of the rotor 20 of FIG. 2A and the wholeproperties of the rotor 40 of FIG. 4.

The characteristics of the rotors 10, 20, 30 and 40 can be applied toall rotors like the rotor 50 of FIG. 5, or selectively applied thereto.

FIG. 6 is a plane view illustrating a rotor for a line-start reluctancemotor in accordance with a sixth embodiment of the present invention.The rotor 60 of FIG. 6 has the whole properties of the rotor 10 of FIG.1A and the whole properties of the rotor 20 of FIG. 2A. Additionally,all flux barriers approach bars in first and second areas of the rotor60.

Although the preferred embodiments of the present invention have beendescribed, it is understood that the present invention should not belimited to these preferred embodiments but various changes andmodifications can be made by one skilled in the art within the spiritand scope of the present invention as hereinafter claimed.

1. A rotor for a line-start reluctance motor, comprising: a core having an axis coupling hole in a coupling direction of a shaft; a plurality of bars formed in the periphery of the core; and a plurality of flux barriers, one and the other ends of the flux barriers approaching the bars formed in first and second areas facing each other at a predetermined angle on a central line of a first axis on a core plane vertical to the coupling direction, at least parts of the centers of the flux barriers passing through a third or fourth area between the first and second areas, surrounding the axis coupling hole at predetermined intervals.
 2. The rotor of claim 1, wherein the flux barriers surround the axis coupling hole in a circular arc shape.
 3. The rotor of claim 1, wherein the flux barriers are continuous.
 4. The rotor of claim 1, wherein the flux barriers are symmetric on a second axis vertical to the first axis on the core plane.
 5. The rotor of claim 1, wherein a rate of an area of the flux barriers to a whole area of the core plane is 0.35 to 0.45.
 6. The rotor of claim 5, wherein the rate of the area is 0.39.
 7. The rotor of claim 1, wherein a rate of a whole width of the flux barriers to a width between the axis coupling hole and the outer circumference of the core is 0.35 to 0.45.
 8. The rotor of claim 7, wherein the rate of the width is 0.405.
 9. The rotor of claim 1, wherein central lines of one and the other ends of the flux barriers and central lines of the bars which the flux barriers approach are disposed in the same directions, the central lines of the bars facing the center of the core.
 10. The rotor of claim 9, wherein the central lines of the bars and the central lines of the flux barriers are formed on the same lines.
 11. The rotor of claim 1, wherein a width of the flux barriers is equal to or smaller than that of the bars which the flux barriers approach.
 12. The rotor of claim 1, wherein intervals between the flux barriers and the bars which the flux barriers approach are constant
 13. The rotor of claim 12, wherein the intervals are less than 0.35 mm.
 14. The rotor of claim 1, wherein a width of the outer circumferences of the bars adjacent to the outer circumference of the core is larger than that of the inner circumferences of the bars adjacent to the flux barriers.
 15. The rotor of claim 1, wherein some of the bars in the first and second areas are not adjacent to the flux barriers.
 16. The rotor of claim 1, wherein intervals between the bars and the outer circumference of the core are all the same.
 17. The rotor of claim 1, wherein the flux barriers are formed between the bars in the third and fourth areas.
 18. The rotor of claim 1, wherein an area of the bars in the third and fourth areas is smaller than that of the bars in the first and second areas.
 19. The rotor of claim 1, wherein intervals between the bars in the third and fourth areas are smaller than those between the bars in the first and second areas.
 20. The rotor of claim 1, wherein a width of the outer circumferences of the bars in the third and fourth areas is larger than that of the outer circumferences of the bars in the first and second areas.
 21. The rotor of claim 1, 15 or 17, wherein an angle of the first and second areas is 100 to 110°.
 22. The rotor of claim 21, wherein the angle is 104°.
 23. The rotor of claim 1 or 17, wherein a length of the bars in the first and second areas is larger than that of the bars in the third and fourth areas.
 24. The rotor of claim 23, wherein at least one flux barrier is formed between a common tangent line of the inner circumferences of the bars in the first and second areas and a common tangent line of the inner circumferences of the bars in the third and fourth areas.
 25. A rotor for a line-start reluctance motor, comprising: a core having an axis coupling hole in a coupling direction of a shaft; a plurality of bars formed in the periphery of the core; and a plurality of flux barriers having their both ends aligned in one direction to approach the bars, respectively, central lines of the bars facing the center of the core and central lines of both ends of the flux barriers being formed in the same directions.
 26. The rotor of claim 25, wherein the central lines of the bars and the central lines of both ends of the flux barriers are formed on the same lines.
 27. The rotor of claim 25, wherein the flux barriers are formed between the bars disposed in a vertical direction to an alignment direction of the flux barriers.
 28. The rotor of claim 25, wherein an area of the bars disposed in the vertical direction to the alignment direction of the flux barriers is smaller than that of the bars disposed in the alignment direction of the flux barriers.
 29. The rotor of claim 25, wherein intervals between the bars disposed in the vertical direction to the alignment direction of the flux barriers are smaller than those between the bars disposed in the alignment direction of the flux barriers.
 30. The rotor of claim 25, wherein a width of the outer circumferences of the bars disposed in the vertical direction to the alignment direction of the flux barriers is larger than that of the outer circumferences of the bars disposed in the alignment direction of the flux barriers.
 31. The rotor of claim 25, wherein a length of the bars disposed in the alignment direction of the flux barriers is larger than that of the bars disposed in the vertical direction to the alignment direction of the flux barriers.
 32. The rotor of claim 31, wherein at least one flux barrier is formed between a common tangent line of the inner circumferences of the bars disposed in the alignment direction of the flux barriers and a common tangent line of the inner circumferences of the bars disposed in the vertical direction to the alignment direction of the flux barriers.
 33. The rotor of claim 25, wherein a width of the flux barriers is equal to or smaller than that of the bars disposed in the alignment direction of the flux barriers.
 34. A rotor for a line-start reluctance motor, comprising: a core having an axis coupling hole in a coupling direction of a shaft; a plurality of bars formed in the periphery of the core; and a plurality of flux barriers having their both ends aligned in one direction to approach the bars, respectively, a width of the flux barriers being equal to or smaller than that of the bars which both ends of the flux barriers approach.
 35. The rotor of claim 33, wherein the flux barriers are formed between the bars disposed in a vertical direction to an alignment direction of the flux barriers.
 36. The rotor of claim 34, wherein an area of the bars disposed in the vertical direction to the alignment direction of the flux barriers is smaller than that of the bars disposed in the alignment direction of the flux barriers.
 37. The rotor of claim 34, wherein intervals between the bars disposed in the vertical direction to the alignment direction of the flux barriers are smaller than those between the bars disposed in the alignment direction of the flux barriers.
 38. The rotor of claim 34, wherein a width of the outer circumferences of the bars disposed in the vertical direction to the alignment direction of the flux barriers is larger than that of the outer circumferences of the bars disposed in the alignment direction of the flux barriers.
 39. The rotor of claim 34, wherein a length of the bars disposed in the alignment direction of the flux barriers is larger than that of the bars disposed in the vertical direction to the alignment direction of the flux barriers.
 40. The rotor of claim 39, wherein at least one flux barrier is formed between a common tangent line of the inner circumferences of the bars disposed in the alignment direction of the flux barriers and a common tangent line of the inner circumferences of the bars disposed in the vertical direction to the alignment direction of the flux barriers.
 41. A rotor for a line-start reluctance motor, comprising: a core having an axis coupling hole in a coupling direction of a shaft; a plurality of bars formed in the periphery of the core; and a plurality of flux barriers aligned in one direction, a length of the bars disposed in an alignment direction of the flux barriers being larger than that of the bars disposed in a vertical direction to the alignment direction of the flux barriers.
 42. The rotor of claim 41, wherein at least one flux barrier is formed between a common tangent line of the inner circumferences of the bars disposed in the alignment direction of the flux barriers and a common tangent line of the inner circumferences of the bars disposed in the vertical direction to the alignment direction of the flux barriers.
 43. The rotor of claim 41, wherein the flux barriers are formed between the bars disposed in the vertical direction to the alignment direction of the flux barriers.
 44. The rotor of claim 41, wherein an area of the bars disposed in the vertical direction to the alignment direction of the flux barriers is smaller than that of the bars disposed in the alignment direction of the flux barriers.
 45. The rotor of claim 41, wherein intervals between the bars disposed in the vertical direction to the alignment direction of the flux barriers are smaller than those between the bars disposed in the alignment direction of the flux barriers.
 46. The rotor of claim 41, wherein a width of the outer circumferences of the bars disposed in the vertical direction to the alignment direction of the flux barriers is larger than that of the outer circumferences of the bars disposed in the alignment direction of the flux barriers. 